Vehicle windshield washer systems include a washer fluid reservoir mounted in the engine compartment. A motor-driven pump draws fluid from the reservoir and pumps the fluid under pressure through conduits connected to the pump housing to spray nozzles in the vicinity of the windshield to dispense the fluid over the windshield.
The washer fluid pump, when activated, rotates an impeller in one of two directions to pump fluid through flow channels in the pump housing to different spray nozzles, one of which may also be located on the rear vehicle window.
Fluid reservoir level sensors are mounted on the reservoir to detect a predetermined low fluid level. A sensor output is used to activate an alarm, such as a light, within the vehicle to signal the driver to replenish the washer fluid.
One typical sensor assembly has a tubular column connected to the side of the fluid reservoir and is fluidically coupled to the reservoir at a bottom end. The fluid level in the column, which corresponds to the level of fluid in the reservoir, is detected by a float disposed within the column. Circuitry connected to the float generates the alarm signal at a predetermined float level.
This type of sensor configuration can be complicated due to the many parts and space consumed by the tubular column. This imposes severe design restrictions on the entire windshield washer assembly due to limited space in the engine compartment. The tubular housing also restricts design freedom for the shape and mounting position of the fluid reservoir.
Another sensor arrangement uses two electrodes having free ends spaced apart in the reservoir. The washer fluid shorts the electrodes when the fluid level is above the electrodes and the electrode ends are completely immersed in the washer fluid. When the electrodes are clear of fluid, an open circuit exists between the electrodes which can be detected by circuitry coupled to the electrodes to generate the low fluid level signal.
Such a sensor design is simpler in construction than the separate tubular column sensor, but is still separately mounted in the reservoir from the washer fluid pump.
The windshield washer fluid pump is typically mounted in a housing adjacent to the fluid reservoir and coupled to a discharge outlet on the reservoir. Typically, a multiple-part housing is used to couple the reservoir discharge outlet to a fluid conduit coupled to the pump housing for the discharge of washer fluid through the pump housing and the attached conduit to the remote spray nozzle.
The separate fluid carrying parts of the pump housing require a seal for fluid tight operation. Typically, the seal is a separate, thin, small gasket mounted between two pump housing parts. The gasket is typically held in position between the two pump housing parts by a snap-fit feature wherein the seal fits into a groove on the outside or between the pump housing parts.
However, due to the thin, flimsy nature of the seal, handling and assembly of the seal onto a seal carrier or in the pump housing parts have proven difficult, thereby frequently resulting in improper seal mounting and lengthy assembly time.
In certain windshield washer configurations, the washer pump is a bidirectional pump having two flow outlets formed in the pump housing. Depending upon a direction of revolution of the pump impeller, only the outlet in the direction of revolution is open; while the other outlet is closed. This alternating flow path switching is controlled by a valve system established by two silicone or rubber membranes, one facing up and the other facing down in valve grooves between two parts of the pump housing. The valves are formed as check valves and alternately open and close flow paths to the respective pump housing outlets in response to the direction of fluid flow created by rotation of the pump impeller.
In addition, the seal carrier also carries a motor shaft seal to seal the connection of the pump motor to the impeller. In prior washer fluid pump assemblies, each of these multiple sealing functions required a separate seal element which was separately mounted onto the carrier. This resulted in a relatively expensive, difficult to assemble pump housing.
Thus, it would be desirable to provide a windshield wiper fluid system which has improved level sensing and sealing characteristics as compared to previously devised windshield washer fluid pump systems.
A windshield washer fluid dispenser apparatus in the form of a pump with an integrated fluid level sensor is disclosed.
In one aspect of the invention, the apparatus includes a windshield washer fluid reservoir having a fluid discharge outlet. A housing having a first fluid inlet and at least one fluid outlet is provided, with the fluid inlet fluidically coupled to the discharge outlet of the reservoir. A pump is mounted in the housing for pumping fluid from the reservoir through the fluid inlet to the fluid outlet. A fluid level sensor is also mounted in the housing and has a sensing end extending from the housing into the reservoir and exposed to fluid in the reservoir.
Preferably, the sensor comprises a pair of sensing electrodes, each having a sensing end, an intermediate portion and an opposed end. The sensing ends of the electrodes are spaced apart and extending outward from the housing into the reservoir for exposure to the washer fluid in the reservoir.
The intermediate portion of each electrode is fixedly mounted in the housing, preferably by insert molding with the housing. The opposed ends of the electrodes are disposed in a connector portion of the housing for connection by an external connector or plug to an external circuit.
In one aspect of the invention, the intermediate portion of the electrodes adjacent to the sensing end has a labyrinth or non-linear shape for secure fixed mounting in the housing by insert molding.
In another aspect of the invention, a pump apparatus for a windshield washer fluid dispenser apparatus is disclosed for use with a washer fluid reservoir. The apparatus includes a pump housing having a fluid inlet for receiving fluid from a reservoir and a fluid outlet for transmitting fluid. A pair of sense electrodes having sensing ends, connector ends and intermediate portions are mounted in the housing, with at least the intermediate portion fixed in the housing. The sensing ends extend from the housing and are adapted for disposition in a washer fluid reservoir so as to be operable to provide a signal depending upon the level of fluid in the reservoir with respect to the position of the sensing ends of the sense electrodes in the reservoir.
The windshield washer pump with integrated fluid level sensor of the present invention uniquely provides a one piece integral pump housing and sensor assembly which simplifies construction of the pump and sensor as well as simplifying mounting of the pump and sensor to a windshield washer fluid reservoir. The number of separate parts in the assembly is minimized to reduce manufacturing costs and simplify assembly.
The sense electrodes are uniquely insert molded in the pump housing to eliminate the separate mounting requirements of the prior art for such electrodes. The electrodes have a labyrinth mounting portion for stable fixed mounting of the electrodes in the housing.
The pump housing itself has snap connected parts for simplified assembly and reduced costs.